{"gene":"ANKRD9","run_date":"2026-06-09T22:02:43","timeline":{"discoveries":[{"year":2018,"finding":"ANKRD9 functions as a substrate receptor subunit of a CUL5-based cullin-RING E3 ubiquitin ligase complex, assembling with CUL5 (not CUL2), ELOB, ELOC, and RNF7 subunits. Both isoforms of inosine monophosphate dehydrogenase (IMPDH1 and IMPDH2) are cognate substrates of this complex; ANKRD9 recognizes IMPDH isoforms and is required for their ubiquitination and proteasomal degradation.","method":"Quantitative proteomics, western blotting, complex reconstitution assays, in vitro ubiquitylation assay","journal":"Biochimica et biophysica acta. Molecular basis of disease","confidence":"High","confidence_rationale":"Tier 1 / Strong — in vitro ubiquitylation assay combined with complex reconstitution and multiple orthogonal methods (proteomics, western blot) in a single study","pmids":["30293565"],"is_preprint":false},{"year":2019,"finding":"ANKRD9 facilitates degradation of IMPDH2 in a metabolically-controlled manner. Under basal conditions ANKRD9 is segregated from cytosolic IMPDH2 in vesicle-like structures. Upon nutrient limitation, ANKRD9 loses its vesicular pattern and co-assembles with IMPDH2 into rod-like filaments. Inhibition of IMPDH2 activity with ribavirin promotes ANKRD9 binding to IMPDH2 rods, while guanosine addition reverses rod formation and restores ANKRD9 to vesicle-like structures. The conserved Cys109-Cys110 motif in ANKRD9 is required for the vesicle-to-rod transition and for IMPDH2 binding and regulation. ANKRD9 knockdown increases IMPDH2 levels and prevents IMPDH2 rod formation upon nutrient limitation.","method":"Fluorescence live imaging, subcellular fractionation, siRNA knockdown, ANKRD9 overexpression, site-directed mutagenesis (Cys109/Cys110 mutants), ribavirin and guanosine treatments","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (imaging, mutagenesis, knockdown, pharmacological perturbations) in a single rigorous study","pmids":["31337707"],"is_preprint":false},{"year":2009,"finding":"ANKRD9 mRNA is dramatically induced in riboflavin-deficiency-induced fatty acid oxidation disorders in chicken liver. Hepatic ANKRD9 mRNA is repressed by thyroid hormone (T3) and fasting, elevated by re-feeding after fasting, and reduced in response to apoptosis. GFP-tagged ANKRD9 localizes to the cytoplasm.","method":"Gene expression analysis (qRT-PCR/microarray), GFP-tagging and transient transfection for localization","journal":"BMB reports","confidence":"Medium","confidence_rationale":"Tier 3 / Weak — single lab, cytoplasmic localization by GFP tagging without functional mutagenesis; expression regulation established but mechanistic link to lipid metabolism inferred rather than directly tested","pmids":["19788857"],"is_preprint":false},{"year":2026,"finding":"ANKRD9 negatively regulates skeletal myogenesis in chicken by directly binding IMPDH2 and promoting its ubiquitin-mediated proteasomal degradation without affecting IMPDH2 mRNA levels. ANKRD9 overexpression inhibits myoblast proliferation and differentiation, while knockdown enhances these processes. In vivo siRNA-mediated ANKRD9 knockdown increases muscle mass and myofiber diameter. Rescue experiments restoring IMPDH2 expression reversed the inhibitory effects of ANKRD9, confirming that IMPDH2 degradation mediates the myogenic inhibition.","method":"siRNA knockdown and overexpression in chicken primary myoblasts, in vivo siRNA injection, rescue experiments with IMPDH2 re-expression, co-immunoprecipitation/binding assays, ubiquitination assays, qRT-PCR for mRNA levels","journal":"Poultry science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct binding, ubiquitination assay, and epistatic rescue in a single lab study; in vivo validation strengthens mechanistic claim but no independent replication","pmids":["41691811"],"is_preprint":false},{"year":2026,"finding":"ANKRD9 couples ATP synthesis and lipoprotein trafficking in intestinal enterocytes. ANKRD9 regulates enzymes within the purine biosynthesis pathway to increase ATP synthesis. Intracellular localization of ANKRD9 is lipid- and ATP-dependent. Inactivation of Ankrd9 in mice reduces intestinal ATP (despite intact mitochondrial and glycolytic function), alters Golgi morphology, delays ApoB/chylomicron trafficking, and causes lipid accumulation in enterocytes along with a lean body phenotype.","method":"Ankrd9 knockout mouse model, intestinal ATP measurements, Golgi morphology imaging, ApoB/chylomicron trafficking assays, lipid accumulation assays, body composition analysis","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic knockout in mice with multiple orthogonal functional readouts (ATP levels, Golgi morphology, chylomicron trafficking, lipid accumulation, body phenotype) in a single rigorous study","pmids":["41826336"],"is_preprint":false},{"year":2026,"finding":"Overexpression of ANKRD9 in chicken primary myoblasts significantly inhibits IMP metabolism, as measured by ELISA, indicating ANKRD9 plays a key role in negative regulation of IMP accumulation through the purine metabolic pathway.","method":"ANKRD9 overexpression in chicken primary myoblasts, ELISA for IMP levels, transcriptomics and metabolomics","journal":"British poultry science","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, single method (ELISA) for the key mechanistic claim; transcriptomic/metabolomic data are associative","pmids":["41769753"],"is_preprint":false}],"current_model":"ANKRD9 is a metabolically-regulated ankyrin repeat protein that acts as a substrate receptor subunit of a CUL5-ELOB-ELOC-RNF7 E3 ubiquitin ligase complex to ubiquitinate IMPDH1/2 for proteasomal degradation; its subcellular localization switches between vesicle-like structures and IMPDH2-containing rod-like filaments in a guanosine/nutrient-dependent manner requiring its conserved Cys109-Cys110 motif, and in intestinal enterocytes it additionally regulates purine biosynthesis enzymes to control ATP availability, Golgi dynamics, and ApoB/chylomicron trafficking during dietary fat absorption."},"narrative":{"mechanistic_narrative":"ANKRD9 is a metabolically regulated ankyrin-repeat protein that functions as the substrate-recognition subunit of a CUL5–ELOB–ELOC–RNF7 cullin-RING E3 ubiquitin ligase, targeting the purine-biosynthesis enzymes IMPDH1 and IMPDH2 for ubiquitination and proteasomal degradation [PMID:30293565]. Its control of IMPDH2 is coupled to cellular nutrient and guanosine status: under basal conditions ANKRD9 is sequestered in vesicle-like structures away from cytosolic IMPDH2, but upon nutrient limitation it relocalizes and co-assembles with IMPDH2 into rod-like filaments, a vesicle-to-rod transition and IMPDH2 binding that requires its conserved Cys109–Cys110 motif; guanosine addition reverses rod formation and restores the vesicular pattern [PMID:31337707]. Through this IMPDH2-degrading activity ANKRD9 acts as a negative regulator of skeletal myogenesis, where its overexpression suppresses myoblast proliferation and differentiation and its knockdown increases muscle mass, effects reversed by restoring IMPDH2 [PMID:41691811]. In intestinal enterocytes ANKRD9 regulates purine-biosynthesis enzymes to sustain ATP synthesis, and its loss in mice lowers intestinal ATP, alters Golgi morphology, delays ApoB/chylomicron trafficking, and produces lipid accumulation with a lean phenotype, linking purine metabolism to dietary fat absorption [PMID:41826336].","teleology":[{"year":2018,"claim":"Established ANKRD9's biochemical identity by defining it as the substrate receptor of a specific CUL5-based E3 ligase and identifying IMPDH1/2 as its degradation substrates, answering what molecular activity the protein carries.","evidence":"Quantitative proteomics, complex reconstitution, and in vitro ubiquitylation assays defining CUL5-ELOB-ELOC-RNF7 assembly and IMPDH ubiquitination","pmids":["30293565"],"confidence":"High","gaps":["Structural basis of IMPDH recognition by the ankyrin repeats not defined","Whether substrates beyond IMPDH1/2 exist not addressed"]},{"year":2019,"claim":"Showed that ANKRD9-mediated IMPDH2 regulation is metabolically gated through a guanosine/nutrient-responsive vesicle-to-rod relocalization requiring the Cys109-Cys110 motif, explaining how substrate engagement is controlled.","evidence":"Live imaging, subcellular fractionation, siRNA knockdown, Cys109/Cys110 mutagenesis, ribavirin and guanosine treatments","pmids":["31337707"],"confidence":"High","gaps":["Mechanism by which the Cys109-Cys110 motif senses metabolic state unknown","Composition and identity of the vesicle-like structures not defined","Whether rod incorporation promotes or inhibits IMPDH2 degradation not fully resolved"]},{"year":2009,"claim":"Provided the earliest functional context by linking ANKRD9 expression to nutritional and hormonal state and lipid/fatty acid oxidation disorders, hinting at a metabolic role before its molecular function was known.","evidence":"Expression profiling in riboflavin-deficient chicken liver, hormonal/fasting/re-feeding regulation, GFP-tagged cytoplasmic localization","pmids":["19788857"],"confidence":"Medium","gaps":["Mechanistic link between ANKRD9 and lipid metabolism inferred, not tested","No functional perturbation performed"]},{"year":2026,"claim":"Demonstrated a physiological output of the ANKRD9-IMPDH2 axis by showing ANKRD9 negatively regulates skeletal myogenesis through IMPDH2 degradation, with epistatic rescue confirming IMPDH2 as the relevant effector.","evidence":"Overexpression/knockdown in chicken myoblasts, in vivo siRNA, co-IP, ubiquitination assays, and IMPDH2 re-expression rescue","pmids":["41691811"],"confidence":"Medium","gaps":["Single-lab study without independent replication","Chicken-specific; relevance to mammalian muscle not tested here"]},{"year":2026,"claim":"Connected ANKRD9 to whole-animal physiology by showing it couples purine-driven ATP synthesis to Golgi dynamics and chylomicron trafficking in enterocytes, establishing a role in dietary fat absorption.","evidence":"Ankrd9 knockout mice with intestinal ATP measurements, Golgi imaging, ApoB/chylomicron trafficking assays, and body composition analysis","pmids":["41826336"],"confidence":"High","gaps":["Direct mechanistic link from IMPDH2/purine enzymes to Golgi and ApoB trafficking not fully resolved","Whether the ATP defect alone explains the trafficking phenotype unclear"]},{"year":2026,"claim":"Added associative metabolic support that ANKRD9 suppresses IMP accumulation via the purine pathway in myoblasts.","evidence":"ANKRD9 overexpression in chicken myoblasts with ELISA for IMP plus transcriptomics/metabolomics","pmids":["41769753"],"confidence":"Low","gaps":["Key claim rests on a single ELISA readout; not independently confirmed","Transcriptomic/metabolomic associations not causally tested"]},{"year":null,"claim":"How ANKRD9's metabolic sensing, IMPDH2 filament dynamics, and downstream control of Golgi/lipoprotein trafficking are mechanistically integrated remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of ANKRD9-IMPDH recognition","Causal chain from ATP/purine flux to Golgi and chylomicron trafficking undefined","Human in vivo relevance of myogenic and intestinal roles not established"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,1,3]},{"term_id":"GO:0016874","term_label":"ligase activity","supporting_discovery_ids":[0]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0]}],"localization":[{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[1,2]},{"term_id":"GO:0031410","term_label":"cytoplasmic vesicle","supporting_discovery_ids":[1]}],"pathway":[{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[0]},{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[4,5]}],"complexes":["CUL5-ELOB-ELOC-RNF7 cullin-RING E3 ubiquitin ligase"],"partners":["IMPDH2","IMPDH1","CUL5","ELOB","ELOC","RNF7"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q96BM1","full_name":"Ankyrin repeat domain-containing protein 9","aliases":[],"length_aa":317,"mass_kda":34.3,"function":"Substrate receptor subunit of a cullin-RING superfamily E3 ligase complex (CUL5-based E3 ubiquitin ligase complex) which mediates the ubiquitination and subsequent proteasomal degradation of target proteins (PubMed:30293565). Depending of the metabolic state of the cell, promotes the proteasomal degradation of IMPDH2, the rate-limiting enzyme in GTP biosynthesis or protects IMPDH2 by stabilizing IMPDH2 filaments assembly (PubMed:30293565, PubMed:31337707). Implicated in different cellular processes, like copper homeostasis and cell proliferation (PubMed:24522796, PubMed:30293565)","subcellular_location":"Cytoplasmic vesicle; Cytoplasm, cytosol","url":"https://www.uniprot.org/uniprotkb/Q96BM1/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/ANKRD9","classification":"Not Classified","n_dependent_lines":2,"n_total_lines":1208,"dependency_fraction":0.0016556291390728477},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/ANKRD9","total_profiled":1310},"omim":[{"mim_id":"618605","title":"ANKYRIN REPEAT DOMAIN-CONTAINING PROTEIN 9; ANKRD9","url":"https://www.omim.org/entry/618605"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in all","driving_tissues":[{"tissue":"heart muscle","ntpm":104.9},{"tissue":"skeletal muscle","ntpm":148.8}],"url":"https://www.proteinatlas.org/search/ANKRD9"},"hgnc":{"alias_symbol":[],"prev_symbol":[]},"alphafold":{"accession":"Q96BM1","domains":[],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q96BM1","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q96BM1-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q96BM1-F1-predicted_aligned_error_v6.png","plddt_mean":81.12},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=ANKRD9","jax_strain_url":"https://www.jax.org/strain/search?query=ANKRD9"},"sequence":{"accession":"Q96BM1","fasta_url":"https://rest.uniprot.org/uniprotkb/Q96BM1.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q96BM1/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q96BM1"}},"corpus_meta":[{"pmid":"29618728","id":"PMC_29618728","title":"Association between DNA methylation in cord blood and maternal smoking: The Hokkaido Study on Environment and Children's Health.","date":"2018","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/29618728","citation_count":36,"is_preprint":false},{"pmid":"35798818","id":"PMC_35798818","title":"EWAS of post-COVID-19 patients shows methylation differences in the immune-response associated gene, IFI44L, three months after COVID-19 infection.","date":"2022","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/35798818","citation_count":25,"is_preprint":false},{"pmid":"31337707","id":"PMC_31337707","title":"ANKRD9 is a metabolically-controlled regulator of IMPDH2 abundance and macro-assembly.","date":"2019","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/31337707","citation_count":24,"is_preprint":false},{"pmid":"30293565","id":"PMC_30293565","title":"ANKRD9 is associated with tumor suppression as a substrate receptor subunit of ubiquitin ligase.","date":"2018","source":"Biochimica et biophysica acta. Molecular basis of disease","url":"https://pubmed.ncbi.nlm.nih.gov/30293565","citation_count":22,"is_preprint":false},{"pmid":"34852967","id":"PMC_34852967","title":"MiR-29b-1-5p regulates the proliferation and differentiation of chicken primary myoblasts and analysis of its effective targets.","date":"2021","source":"Poultry science","url":"https://pubmed.ncbi.nlm.nih.gov/34852967","citation_count":18,"is_preprint":false},{"pmid":"19788857","id":"PMC_19788857","title":"Regulation of ANKRD9 expression by lipid metabolic perturbations.","date":"2009","source":"BMB reports","url":"https://pubmed.ncbi.nlm.nih.gov/19788857","citation_count":17,"is_preprint":false},{"pmid":"38900908","id":"PMC_38900908","title":"Embryonic alcohol exposure in zebrafish predisposes adults to cardiomyopathy and diastolic dysfunction.","date":"2024","source":"Cardiovascular research","url":"https://pubmed.ncbi.nlm.nih.gov/38900908","citation_count":9,"is_preprint":false},{"pmid":"35928108","id":"PMC_35928108","title":"Mechanism of Lysoforte in Improving Jejuna Morphology and Health in Broiler Chickens.","date":"2022","source":"Frontiers in veterinary science","url":"https://pubmed.ncbi.nlm.nih.gov/35928108","citation_count":2,"is_preprint":false},{"pmid":"41691811","id":"PMC_41691811","title":"ANKRD9 negatively regulates chicken myogenesis through ubiquitin-mediated regulation of IMPDH2.","date":"2026","source":"Poultry science","url":"https://pubmed.ncbi.nlm.nih.gov/41691811","citation_count":0,"is_preprint":false},{"pmid":"41769753","id":"PMC_41769753","title":"Integrative 'omics' analysis elucidates the role of the gene ANKRD9 in modulating chicken primary myoblast IMP metabolism via the purine metabolic pathway.","date":"2026","source":"British poultry science","url":"https://pubmed.ncbi.nlm.nih.gov/41769753","citation_count":0,"is_preprint":false},{"pmid":"41826336","id":"PMC_41826336","title":"Enterocytes rely on purine biosynthesis/salvage pathway to facilitate dietary fat absorption.","date":"2026","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/41826336","citation_count":0,"is_preprint":false},{"pmid":"41940665","id":"PMC_41940665","title":"Diabetes affects the composition of the respiratory tract microbiome and transcriptome in patients with viral pneumonia.","date":"2026","source":"Microbiology spectrum","url":"https://pubmed.ncbi.nlm.nih.gov/41940665","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":8255,"output_tokens":1974,"usd":0.027187,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8932,"output_tokens":2787,"usd":0.057168,"stage2_stop_reason":"end_turn"},"total_usd":0.084355,"stage1_batch_id":"msgbatch_0179Z2pxRYBsXi2xADneafRw","stage2_batch_id":"msgbatch_01LaY9ZaVdgjWArcZo9eqQE5","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2018,\n      \"finding\": \"ANKRD9 functions as a substrate receptor subunit of a CUL5-based cullin-RING E3 ubiquitin ligase complex, assembling with CUL5 (not CUL2), ELOB, ELOC, and RNF7 subunits. Both isoforms of inosine monophosphate dehydrogenase (IMPDH1 and IMPDH2) are cognate substrates of this complex; ANKRD9 recognizes IMPDH isoforms and is required for their ubiquitination and proteasomal degradation.\",\n      \"method\": \"Quantitative proteomics, western blotting, complex reconstitution assays, in vitro ubiquitylation assay\",\n      \"journal\": \"Biochimica et biophysica acta. Molecular basis of disease\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — in vitro ubiquitylation assay combined with complex reconstitution and multiple orthogonal methods (proteomics, western blot) in a single study\",\n      \"pmids\": [\"30293565\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"ANKRD9 facilitates degradation of IMPDH2 in a metabolically-controlled manner. Under basal conditions ANKRD9 is segregated from cytosolic IMPDH2 in vesicle-like structures. Upon nutrient limitation, ANKRD9 loses its vesicular pattern and co-assembles with IMPDH2 into rod-like filaments. Inhibition of IMPDH2 activity with ribavirin promotes ANKRD9 binding to IMPDH2 rods, while guanosine addition reverses rod formation and restores ANKRD9 to vesicle-like structures. The conserved Cys109-Cys110 motif in ANKRD9 is required for the vesicle-to-rod transition and for IMPDH2 binding and regulation. ANKRD9 knockdown increases IMPDH2 levels and prevents IMPDH2 rod formation upon nutrient limitation.\",\n      \"method\": \"Fluorescence live imaging, subcellular fractionation, siRNA knockdown, ANKRD9 overexpression, site-directed mutagenesis (Cys109/Cys110 mutants), ribavirin and guanosine treatments\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (imaging, mutagenesis, knockdown, pharmacological perturbations) in a single rigorous study\",\n      \"pmids\": [\"31337707\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"ANKRD9 mRNA is dramatically induced in riboflavin-deficiency-induced fatty acid oxidation disorders in chicken liver. Hepatic ANKRD9 mRNA is repressed by thyroid hormone (T3) and fasting, elevated by re-feeding after fasting, and reduced in response to apoptosis. GFP-tagged ANKRD9 localizes to the cytoplasm.\",\n      \"method\": \"Gene expression analysis (qRT-PCR/microarray), GFP-tagging and transient transfection for localization\",\n      \"journal\": \"BMB reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, cytoplasmic localization by GFP tagging without functional mutagenesis; expression regulation established but mechanistic link to lipid metabolism inferred rather than directly tested\",\n      \"pmids\": [\"19788857\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"ANKRD9 negatively regulates skeletal myogenesis in chicken by directly binding IMPDH2 and promoting its ubiquitin-mediated proteasomal degradation without affecting IMPDH2 mRNA levels. ANKRD9 overexpression inhibits myoblast proliferation and differentiation, while knockdown enhances these processes. In vivo siRNA-mediated ANKRD9 knockdown increases muscle mass and myofiber diameter. Rescue experiments restoring IMPDH2 expression reversed the inhibitory effects of ANKRD9, confirming that IMPDH2 degradation mediates the myogenic inhibition.\",\n      \"method\": \"siRNA knockdown and overexpression in chicken primary myoblasts, in vivo siRNA injection, rescue experiments with IMPDH2 re-expression, co-immunoprecipitation/binding assays, ubiquitination assays, qRT-PCR for mRNA levels\",\n      \"journal\": \"Poultry science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct binding, ubiquitination assay, and epistatic rescue in a single lab study; in vivo validation strengthens mechanistic claim but no independent replication\",\n      \"pmids\": [\"41691811\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"ANKRD9 couples ATP synthesis and lipoprotein trafficking in intestinal enterocytes. ANKRD9 regulates enzymes within the purine biosynthesis pathway to increase ATP synthesis. Intracellular localization of ANKRD9 is lipid- and ATP-dependent. Inactivation of Ankrd9 in mice reduces intestinal ATP (despite intact mitochondrial and glycolytic function), alters Golgi morphology, delays ApoB/chylomicron trafficking, and causes lipid accumulation in enterocytes along with a lean body phenotype.\",\n      \"method\": \"Ankrd9 knockout mouse model, intestinal ATP measurements, Golgi morphology imaging, ApoB/chylomicron trafficking assays, lipid accumulation assays, body composition analysis\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic knockout in mice with multiple orthogonal functional readouts (ATP levels, Golgi morphology, chylomicron trafficking, lipid accumulation, body phenotype) in a single rigorous study\",\n      \"pmids\": [\"41826336\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"Overexpression of ANKRD9 in chicken primary myoblasts significantly inhibits IMP metabolism, as measured by ELISA, indicating ANKRD9 plays a key role in negative regulation of IMP accumulation through the purine metabolic pathway.\",\n      \"method\": \"ANKRD9 overexpression in chicken primary myoblasts, ELISA for IMP levels, transcriptomics and metabolomics\",\n      \"journal\": \"British poultry science\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, single method (ELISA) for the key mechanistic claim; transcriptomic/metabolomic data are associative\",\n      \"pmids\": [\"41769753\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"ANKRD9 is a metabolically-regulated ankyrin repeat protein that acts as a substrate receptor subunit of a CUL5-ELOB-ELOC-RNF7 E3 ubiquitin ligase complex to ubiquitinate IMPDH1/2 for proteasomal degradation; its subcellular localization switches between vesicle-like structures and IMPDH2-containing rod-like filaments in a guanosine/nutrient-dependent manner requiring its conserved Cys109-Cys110 motif, and in intestinal enterocytes it additionally regulates purine biosynthesis enzymes to control ATP availability, Golgi dynamics, and ApoB/chylomicron trafficking during dietary fat absorption.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"ANKRD9 is a metabolically regulated ankyrin-repeat protein that functions as the substrate-recognition subunit of a CUL5–ELOB–ELOC–RNF7 cullin-RING E3 ubiquitin ligase, targeting the purine-biosynthesis enzymes IMPDH1 and IMPDH2 for ubiquitination and proteasomal degradation [#0]. Its control of IMPDH2 is coupled to cellular nutrient and guanosine status: under basal conditions ANKRD9 is sequestered in vesicle-like structures away from cytosolic IMPDH2, but upon nutrient limitation it relocalizes and co-assembles with IMPDH2 into rod-like filaments, a vesicle-to-rod transition and IMPDH2 binding that requires its conserved Cys109–Cys110 motif; guanosine addition reverses rod formation and restores the vesicular pattern [#1]. Through this IMPDH2-degrading activity ANKRD9 acts as a negative regulator of skeletal myogenesis, where its overexpression suppresses myoblast proliferation and differentiation and its knockdown increases muscle mass, effects reversed by restoring IMPDH2 [#3]. In intestinal enterocytes ANKRD9 regulates purine-biosynthesis enzymes to sustain ATP synthesis, and its loss in mice lowers intestinal ATP, alters Golgi morphology, delays ApoB/chylomicron trafficking, and produces lipid accumulation with a lean phenotype, linking purine metabolism to dietary fat absorption [#4].\",\n  \"teleology\": [\n    {\n      \"year\": 2018,\n      \"claim\": \"Established ANKRD9's biochemical identity by defining it as the substrate receptor of a specific CUL5-based E3 ligase and identifying IMPDH1/2 as its degradation substrates, answering what molecular activity the protein carries.\",\n      \"evidence\": \"Quantitative proteomics, complex reconstitution, and in vitro ubiquitylation assays defining CUL5-ELOB-ELOC-RNF7 assembly and IMPDH ubiquitination\",\n      \"pmids\": [\"30293565\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Structural basis of IMPDH recognition by the ankyrin repeats not defined\",\n        \"Whether substrates beyond IMPDH1/2 exist not addressed\"\n      ]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Showed that ANKRD9-mediated IMPDH2 regulation is metabolically gated through a guanosine/nutrient-responsive vesicle-to-rod relocalization requiring the Cys109-Cys110 motif, explaining how substrate engagement is controlled.\",\n      \"evidence\": \"Live imaging, subcellular fractionation, siRNA knockdown, Cys109/Cys110 mutagenesis, ribavirin and guanosine treatments\",\n      \"pmids\": [\"31337707\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Mechanism by which the Cys109-Cys110 motif senses metabolic state unknown\",\n        \"Composition and identity of the vesicle-like structures not defined\",\n        \"Whether rod incorporation promotes or inhibits IMPDH2 degradation not fully resolved\"\n      ]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Provided the earliest functional context by linking ANKRD9 expression to nutritional and hormonal state and lipid/fatty acid oxidation disorders, hinting at a metabolic role before its molecular function was known.\",\n      \"evidence\": \"Expression profiling in riboflavin-deficient chicken liver, hormonal/fasting/re-feeding regulation, GFP-tagged cytoplasmic localization\",\n      \"pmids\": [\"19788857\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Mechanistic link between ANKRD9 and lipid metabolism inferred, not tested\",\n        \"No functional perturbation performed\"\n      ]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Demonstrated a physiological output of the ANKRD9-IMPDH2 axis by showing ANKRD9 negatively regulates skeletal myogenesis through IMPDH2 degradation, with epistatic rescue confirming IMPDH2 as the relevant effector.\",\n      \"evidence\": \"Overexpression/knockdown in chicken myoblasts, in vivo siRNA, co-IP, ubiquitination assays, and IMPDH2 re-expression rescue\",\n      \"pmids\": [\"41691811\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Single-lab study without independent replication\",\n        \"Chicken-specific; relevance to mammalian muscle not tested here\"\n      ]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Connected ANKRD9 to whole-animal physiology by showing it couples purine-driven ATP synthesis to Golgi dynamics and chylomicron trafficking in enterocytes, establishing a role in dietary fat absorption.\",\n      \"evidence\": \"Ankrd9 knockout mice with intestinal ATP measurements, Golgi imaging, ApoB/chylomicron trafficking assays, and body composition analysis\",\n      \"pmids\": [\"41826336\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Direct mechanistic link from IMPDH2/purine enzymes to Golgi and ApoB trafficking not fully resolved\",\n        \"Whether the ATP defect alone explains the trafficking phenotype unclear\"\n      ]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Added associative metabolic support that ANKRD9 suppresses IMP accumulation via the purine pathway in myoblasts.\",\n      \"evidence\": \"ANKRD9 overexpression in chicken myoblasts with ELISA for IMP plus transcriptomics/metabolomics\",\n      \"pmids\": [\"41769753\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"Key claim rests on a single ELISA readout; not independently confirmed\",\n        \"Transcriptomic/metabolomic associations not causally tested\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How ANKRD9's metabolic sensing, IMPDH2 filament dynamics, and downstream control of Golgi/lipoprotein trafficking are mechanistically integrated remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No structural model of ANKRD9-IMPDH recognition\",\n        \"Causal chain from ATP/purine flux to Golgi and chylomicron trafficking undefined\",\n        \"Human in vivo relevance of myogenic and intestinal roles not established\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 1, 3]},\n      {\"term_id\": \"GO:0016874\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [1, 2]},\n      {\"term_id\": \"GO:0031410\", \"supporting_discovery_ids\": [1]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [4, 5]}\n    ],\n    \"complexes\": [\n      \"CUL5-ELOB-ELOC-RNF7 cullin-RING E3 ubiquitin ligase\"\n    ],\n    \"partners\": [\n      \"IMPDH2\",\n      \"IMPDH1\",\n      \"CUL5\",\n      \"ELOB\",\n      \"ELOC\",\n      \"RNF7\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":4,"faith_total":4,"faith_pct":100.0}}